Sensing the World Requires Intelligent Design
How do our bodies make sense of the external world? Through our senses, of course; at least they are the entry points of data into the mind. Behind those senses are remarkable mechanisms that we use but do not actively operate. The design in their automatic operations is slowly being revealed with better observing techniques.
- Sensing sound with motors: “From grinding heavy metal to soothing ocean waves, the sounds we hear are all perceptible thanks to the vibrations felt by tiny molecular motors in the hair cells of the inner ear,” began an article on PhysOrg.
A single mutation – one amino acid change – in a molecular motor protein called myo1c is enough to disrupt the function of the myosin motor in the hair cell and cause hearing loss. The mutation causes a reduced sensitivity, perhaps due to making it spend less time attached to actin filaments. The amino acid is “highly conserved” (unevolved) throughout the superfamily of myosin motors, the article said.
- Sensing light with circuits: A novel microscope technique has allowed scientists at Max Planck Institute to decode the eye’s complex circuitry, Science Daily reported. “The properties of optical stimuli need to be conveyed from the eye to the brain,” the 03/31/2008).
One example of pre-processing accomplished by ganglion cells is responding to light moving in a particular direction. “This direction selectivity is generated by inhibitory interneurons that influence the activity of the ganglion cells through their synapses.”
Just as with man-made network protocols, the scientists “discovered that the distribution of the synapses between ganglion cells and interneurons follows highly specific rules.” These ganglion cells intercept and process the visual information before it is received by the brain. The article described various rules the network of cells follow in activating or inhibiting visual information.
- Sensing time with clocks: All living things follow “circadian rhythms,” biological responses to changes in time of day, month, and year. As in other mammals, the human master clock is located in the brain – specifically, in the suprachiasmatic nucleus (SCN), a group of nerve cells in the hypothalamus near the visual cortex. In response to its data inputs, the SCN can direct the brain to produce more or less melatonin, a hormone that induces sleep.
Live Science described how the SCN works. There are internal inputs, like genes and proteins produced in the body, and external inputs from the senses. “Biological clocks aren’t made of cogs and wheels, but rather groups of interacting molecules in cells throughout the body,” the article said. One of the proteins is aptly named CLOCK – “an essential component in directing circadian rhythms in humans, fruit flies, mice, fungi and other organisms.” Another is SIRT1, which senses energy use in cells. The balance of these factors affects how the SCN directs the body to respond to light and darkness and other factors.
Disruption of the biological clock can lead to a host of problems. Jet lag is a common example. Fortunately, clock repair is available for that: “Eventually your body is able to adjust its circadian rhythms to the new environment” by a kind of clock reset. Other dysfunctions, though, can lead to more serious problems, like “obesity, depression and seasonal affective disorder.” That’s because “hormone production, hunger, cell regeneration and body temperature” are some of the processes that rely on accurate circadian rhythms.
All sensory inputs must be processed by the brain. Fortunately, the brain, like good computer systems, has redundancy mechanisms that give it “plasticity” – the ability to change as we learn, or as parts become damaged. Science Daily described how researchers at the University of Michigan Medical School are testing mice to see how “the plasticity of the brain allowed mice to restore critical functions related to learning and memory after the scientists suppressed the animals’ ability to make certain new brain cells.”
Fault-tolerant artificial networks, like the power grid and the internet, provide for alternate routes when hubs become unavailable. Similarly, we have “mechanisms by which the brain compensates for disruptions and reroutes neural functioning,” the article said. Part of this is recovering from loss of the ability to make new brain cells by giving existing cells more activity and longer life spans.
“It’s amazing how the brain is capable of reorganizing itself in this manner,” Geoffrey Murphy, an associate professor of molecular and integrative physiology at the medical school said. “Right now, we’re still figuring out exactly how the brain accomplishes all this at the molecular level, but it’s sort of comforting to know that our brains are keeping track of all of this for us.”
It makes sense that readers will sense the wonder of the senses a little more after reading these sensible articles, free as they were of evolutionary nonsense.